USING SOIL TEXTURE IN FORECAST AVAILABLE WATER

A. Khalaf, M.; M. Al-Qubacy, A.

	USING SOIL TEXTURE IN FORECAST AVAILABLE WATER
The Iraqi Journal of Agricultural Science
Article 1, Volume 43, Issue 0, 2013, Pages 22-33
Authors
M. A. Khalaf; A. M. Al-Qubacy
Abstract
An available data of 173 different soil samples of different textural classes from different regions of Iraq were used to forecast available water. Particle size distribution was estimated and 11 classes of texture were identified. Also, bulk density and moisture content at 33, 1500 KPa tension were measured, then available water were calculated. Analysis of variance with and without intercept constant was used to estimate a linear relationships between available water as a response variable and each of; soil moisture at field capacity and soil particles percentages as explanatory variables. In addition, fictitious variables approach was used to express the relation of texture, which calculated in laboratory (twelve classes system of soil texture classification) and estimated by feeling (triple classes system of soil texture classification) as an index of available water in soil. The efficiency of soil in supplying water to plant and prediction power of derived estimation models were calculated. Results of this study showed that available water is significantly and positively correlated with each of silt and clay percentage, and negatively with sand percentage. Also, silty clay soil was superior among all other texture classes in soil water supply efficiency. Although, all derived mathematical models were efficient to estimate available water in soil regardless of the explanatory variables type, yet use of the model that depends on soil feeling of texture was the best from practical point of view because it is easy, quick and low cost when applied. Soils differ in their moisture characteristics silty clay soils detain more water at the field capacity and more of the available water. While the water content at the field capacity and the available water may reaches the lowest limits in sandy soils. Water content at the field capacity and the available water is positively significant correlated with clay and silt separates while it goes reversible significant correlated with sand separate.

Statistics Article View: 202 PDF Download: 161